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INSTRUCTION SET REFERENCE
RSQRTSSÂScalar Single-FP Square Root Reciprocal (Continued)
Intel C/C++ Compiler Intrinsic Equivalent
__m128 _mm_rsqrt_ss(__m128 a)
Computes the approximation of the reciprocal of the square root of the lower SP FP value of a;
the upper three SP FP values are passed through.
Numeric Exceptions
None.
Protected Mode Exceptions
#GP(0)
For an illegal memory operand effective address in the CS, DS, ES, FS, or
GS segments.
#SS(0)
For an illegal address in the SS segment.
#PF (fault-code) For a page fault.
#UD
If CR0.EM = 1.
#NM
If TS bit in CR0 is set.
#AC
For unaligned memory reference. To enable #AC exceptions, three condi-
tions must be true(CR0.AM is set; EFLAGS.AC is set; current CPL is 3)
Real Address Mode Exceptions
Interrupt 13
If any part of the operand would lie outside of the effective address space
from 0 to 0FFFFH.
#UD
If CR0.EM = 1.
#NM
If TS bit in CR0 is set.
Virtual 8086 Mode Exceptions
Same exceptions as in Real Address Mode.
#AC
For unaligned memory reference if the current privilege level is 3.
#PF (fault-code) For a page fault.
Comments
RSQRTSS is not affected by the rounding control in MXCSR. Denormal inputs are treated as
zeroes (of the same sign) and underflow results are always flushed to zero, with the sign of the
operand.
